A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases although they don't often hydrolyze ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered calcium pumps. For example, muscle cells transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a resting muscle cell's cytosol has a free calcium ion concentration of 10-7 while the concentration in the SR is 10-2, then how is the ATPase acting?

Metabolism is a series of chemical reactions that occur in the body's cells to provide energy for vital processes and the synthesis of new organic material.  Metabolism includes many interconnected pathways that capture energy and maximize its use.  These pathways include: Anabolism: Uses energy to make macromolecules and biomolecular polymers Catabolism: Releases energy when these are broken down into simpler molecules  Metabolism involves a vast array of chemical reactions, but most fall under a few basic types of reactions that involve the transfer of functional groups of atoms and... Show more

Metabolism is a series of chemical reactions that occur in the body's cells to provide energy for vital processes and the synthesis of new organic material. 

Metabolism includes many interconnected pathways that capture energy and maximize its use. 
These pathways include:
Anabolism: Uses energy to make macromolecules and biomolecular polymers
Catabolism: Releases energy when these are broken down into simpler molecules 

Metabolism involves a vast array of chemical reactions, but most fall under a few basic types of reactions that involve the transfer of functional groups of atoms and their bonds within molecules. 

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